This invention relates to surgical apparatus, and more particularly to safety mechanisms for use in surgical apparatus for occluding or ligating and dividing body tissue.
Ligating and dividing surgical instruments have typically used metal staples, fasteners, or ligatures to ligate organic tissue structures such as blood vessels. One such system is disclosed in Spasiano et al. U.S. Pat. No. 3,955,581. The apparatus described in that patent operates in three stages to positively control the operations of its metal staple-carrying cartridge. The main body of the cartridge is moved forward toward an anvil assembly fixed on the instrument, thereby enclosing the tissue structure within the jaws of the cartridge. A pair of metal staples is then pushed forward to encircle the tissue structure at spaced apart locations. The staples are crimped or clinched against the fixed anvil assembly to ligate the tissue at the locations of the staples. Finally, a knife blade advances to the fixed anvil assembly and divides the tissue structure intermediate the two staples.
Green et al. U.S. Pat. No. 4,086,926 describes another metal staple-carrying cartridge which operates in three stages. Two laterally spaced metal staples are formed around a tissue structure by means of a fixed anvil assembly, thus ligating the tissue structure. A knife then advances to the fixed anvil assembly and divides the ligated structure between the staples. The staple feeding arrangement in that apparatus comprises a pair of belts, each carrying a plurality of staples.
Another ligating and dividing instrument using metal staples as ligatures and a fixed anvil assembly against which the staples are formed is shown in Green U.S. Pat. No. 4,349,028.
For certain surgical procedures, ligatures in the form of fasteners or clips of X-ray-transparent plastic or plastic-like materials may be preferable to X-ray-opaque metal staples. For convenience herein, all such plastic or plastic-like materials will be referred to generically as plastic-like materials. In addition to X-ray transparency, clips of plastic-like material also have the advantage that they can be made biologically absorbable.
Clips of plastic-like material cannot be simply substituted for metal staples in prior ligating and dividing instruments because plastic-like clips cannot be closed by clinching or crimping in the way that metal staples are clinched or crimped. Unlike metal staples, plastic-like clips will not hold a shape to which they are deformed unless parts of the clip mechanically interlock with one another. Thus the means employed in prior ligating and dividing instruments for clinching or crimping metal staples around the tissue are not suitable for use with plastic-like clips. The problems of storing and feeding plastic-like clips are also different from those associated with metal staples.
It is desirable to provide ligating and dividing instruments with means to assure that the two spaced apart clips have been or will be applied to the tissue before allowing the knife to cut the tissue between the clips. Several of the prior art ligating and dividing instruments have such means, but those prior art safety mechanisms may not be entirely suitable for use in ligating and dividing instruments which employ plastic-like clips. This may be due to differences between metal and plastic-like clips and/or to differences between the structures used to apply these different types of clips. For example, the mechanisms used to apply plastic-like clips may require more delicate clip pushers, so that the clip pushers themselves cannot be used as in some prior art ligating and dividing instruments to effectively lock the instrument if a clip is not present in front of either or both of the clip pushers.
It is therefore an object of this invention to provide improved safety mechanisms for ligating and dividing instruments.
It is another object of this invention to provide safety mechanisms for ligating and dividing instruments of the type which apply plastic-like clips.